In some storage systems, a switch apparatus connects multiple host apparatus and multiple storage apparatus over a network to manage data exchange.
In order to effectively use physical storage areas in multiple storage apparatus in a storage system, a virtualization technology for storage apparatus is available. The virtualization for storage apparatus allows the definition of a virtual storage area including a combination of multiple storage apparatus. In some cases, a switch apparatus may manage the virtualization for storage apparatus. The switch apparatus connects between the multiple storage apparatus and a host apparatus. The related art is disclosed in Japanese Laid-open Patent Publication No. 2003-271425, Japanese Laid-open Patent Publication No. 2006-331458, Japanese Laid-open Patent Publication No. 2003-150414 and Japanese Laid-open Patent Publication No. 07-160548.
A switch apparatus may manage storage apparatus having different processing performances from the reception of a processing instruction for data reading or writing to the transmission of a response to the processing instruction. The virtual storage area managed by the switch apparatus includes physical storage areas in the storage apparatus having different processing performances. Therefore, the time from the transmission by a host apparatus of a processing instruction for data reading or writing to the switch apparatus to the reception by the host apparatus of the result of the processing instruction from the switch apparatus may differ in accordance with the performance of the storage apparatus.